Fluid vane motor/pump

ABSTRACT

A motor/pump (10) comprises a housing (12) defining a cavity (18) between sealed ends (14 and 16). Rotor (24) having a substantially hollow body (26) is supported by the housing (12) for rotation within the cavity (18) about a rotation axis (28) which is parallel to but offset from longitudinal axis (30) of the cavity (18). A plurality of vanes (32) are retained by the rotor (34) for movement radially of the rotation axis (28). ne vanes (32), rotor (24) and housing (12) are juxtaposed so that a substantially sealed chamber is formed between adjacent vanes (32), inner surface (34) of housing (12) and outer circumferential surface (36) of the rotor body (26). First and second ports (20, 22) are formed in the housing (12) and located so as to be disposed in different chambers. A split sleeve (122) is disposed within the rotor (24) for biasing the vanes (32) radially outwardly from the rotation axis (28) wherein axially opposite ends of said vanes (32) are disposed inboard of opposite first and second ends of said rotor body so that in use only a length of said axially opposite ends of each vane which extend beyond an outer peripheral surface (36) of said rotor body can slidingly contact respective adjacent ends of said housing (46, 56).

FIELD OF THE INVENTION

The present invention relates to an apparatus capable for use as a pumpor motor, and in particular, to a fluid Vane pump/motor.

BACKGROUND OF THE INVENTION

Typically, fluid vane motors comprise a housing having a cylindricalbore closed by end plates and a rotor mounted for rotation within thebore. The rotor is in the form of a solid cylindrical billet of metalwith longitudinally extending slots formed about its periphery. The axisof rotation of the rotor is parallel to but offset from the longitudinalaxis of the housing. A plurality of vanes are supported in respectivelongitudinal slots in the rotor in a manner so as to allow movement inthe radial direction. Fluid chambers are formed between adjacent vanes,the volume of the chambers varying as the rotor rotates. Whenfunctioning as a pump, the chambers act to displace fluid from an inletin the housing to an outlet, and when acting as a motor, the chambersallow for the release of pressure of a pressurised fluid to causerotation of a shaft attached to the rotor.

Conventional fluid vane motors/pumps are notoriously inefficient due toleakage of fluid between adjacent chambers via leakage paths formedabout the periphery of the vanes as well as through the rotor itself.Additionally, high frictional losses occur due to the substantialcontact area between the peripheral edges of the vanes and end plates ofthe housing.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an apparatus capablefor use as a pump or motor of increased efficiency.

According to the present invention there is provided an apparatuscapable for use as a pump or motor, said apparatus comprising:

a housing having sealed ends and provided with a cavity between saidends, said housing further including first and second ports bothallowing fluid communication between the interior and exterior of saidhousing;

a rotor having a substantially hollow rotor body supported by saidhousing for rotation within said cavity about a rotation axis extendingparallel to and offset from a longitudinal axis of said cavity, saidrotor body having opposite first and second ends which includerespective portions of reduced diameter with respect to an intermediateportion of said rotor body;

a plurality of slots formed in said rotor body extending between saidopposite first and second ends and terminating in and inboard of saidreduced diameter portions; and,

a plurality of vanes, individual ones of which are slidably retained inseparate slots for movement radially of said rotation axis;

said vanes, rotor and housing juxtaposed so that a substantially sealedchamber is formed between adjacent vanes, an inner circumferentialsurface of said housing and said rotor, and wherein said first andsecond ports are disposed in different ones of said chambers.

Preferably said opposite ends of each slot are arcuate in shape.

Preferably there is provided a seal about each of said reduced diameterportions, said seals being seated so as to cover the opposite ends ofeach slot and sealing abut axially opposite ends of said vanes.

Preferably each end of said housing is provided with a stepped innersurface formed by the junction of two faces and each seal can makesealing contact with both of said faces of an adjacent end of saidhousing.

Preferably a groove extending radially from each end of each slot isformed on a surface at each of said first and second ends interior ofsaid rotor body for receiving axially opposite ends of a vane receivedin that slot.

Preferably said grooves on said interior surface at said first end ofsaid rotor body extend beyond the centre of said rotor body.

In an alternate embodiment said interior surface at said first end ofsaid rotor body is provided with a circular recess centered about saidrotation axis and the grooves formed on this interior surface extendsradially from the end of the slots near said first end to said circularrecess.

Preferably said rotor comprises a shaft extending from the first end ofsaid rotor body and through an aperture formed in a first of said endsof said housing, wherein when said apparatus is used as a pump, torquecan be applied to said shaft to impart rotational motion to said rotor,and when said apparatus is used as a motor, said shaft can act as apower take off.

Preferably the second end of said rotor body opposite said shaft isprovided with a recess for receiving a stub shaft formed on a second ofsaid ends of said housing for rotatably supporting said second end ofsaid rotor body.

Preferably said axially opposite edges of said vanes are formed witharcuate surfaces for sliding and substantially sealing contact withrespective adjacent first and second ends of said housing.

Preferably the radially remote edge of each vane is formed with anarcuate surface for sliding and substantially sealing contact with saidinner circumferential surface of said housing.

Preferably said apparatus further comprises biasing means disposedwithin said rotor body for biasing said vanes radially outwardly towardssaid inner circumferential surface of said housing.

Preferably a recess is formed in the radially inner edge of each vaneinboard of axially opposite ends of each vane for receiving said biasingmeans.

Preferably said rotor comprises a shaft extending from the first end ofsaid rotor body and through an aperture formed in a first of said endsof said housing, wherein when said apparatus is used as a pump, torquecan be applied to said shaft to impart rotational motion to said rotor,and when said apparatus is used as a motor, said shaft can act as apower take off.

Preferably said resilient element comprises one of a split sleeve or atube of resilient material; a length of natural or synthetic rubbertubing or rod; a tube or rod made of plastics material; a flat sectionhelical-spring fitted axially within said rotor body; a solid or hollowrod or tube of material provided with resilient circumferentially spacedinserts at intervals corresponding to the location of said vanes. In analternate embodiment, said biasing means comprises a pressurised fluidretained within said rotor body.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described by way ofexample only, with reference to the accompanying drawings in which:

FIG. 1 is an axial section and partly exploded view of an embodiment ofan apparatus according to the present invention;

FIG. 2 is an end elevation view of one end of a rotor incorporated inthe apparatus shown in FIG. 1;

FIG. 3 is an end elevation of an opposite end of the rotor shown in FIG.2;

FIG. 4 is a side elevation of the rotor shown in FIGS. 1 and 2;

FIG. 5A is a side elevation of a vane incorporated in the apparatusshown in FIG. 1;

FIG. 5B is a bottom elevation of the vane shown in FIG. 5A;

FIG. 5C is a view of Section A--A of the vane shown in FIG. 5A:

FIG. 6A is a side elevation of a biasing element incorporated in theapparatus shown in FIG. 1;

FIG. 6B is an end elevation of the biasing element shown in FIG. 6A;

FIG. 7 is an axial section and partly exploded view of a secondembodiment of the apparatus:

FIG. 8 is an end elevation of an end of the rotor shown in FIG. 7;

FIG. 9A is a side elevation of a second embodiment of a vane used in thepresent apparatus;

FIG. 9B is a bottom view of the vane shown in FIG. 9A; and

FIG. 9C is a view of Section A--A of the vane shown in FIG. 9A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, it can be seen that an apparatus 10 capable for useas a pump or motor comprises a housing 12 having sealed ends 14 and 16and provided with a cavity 18 between said ends 14 and 16. First andsecond ports 20 and 22 are also formed in the housing 12 for allowingfluid communication between the interior and exterior of the housing 12.Rotor 24 having a substantially hollow body 26 is supported by thehousing 12 for rotation within the cavity 18 about a rotation axis 28which is parallel to but offset from longitudinal axis 30 of the cavity18. A plurality of vanes 32 are retained by the rotor 24 for movementradially of the rotation axis 28. The vanes 32, rotor 24 and housing 12are juxtaposed sb that a substantially sealed chamber is formed betweenadjacent vanes 32, inner surface 34 of the housing 12 and outercircumferential surface 36 of the rotor body 26. The first and secondports 20 and 22 are disposed in different chambers.

The housing 12 is composed of a cylindrical member 38, the interior ofwhich forms cavity 18. Ends 14 and 16 of the housing 12 are in the formof plates 40 and 42 respectively which can be bolted to opposite ends ofthe cylindrical element 38. As is apparent from FIG. 1, the surface ofeach of the plates 40 and 42 facing the rotor 24 is stepped In the caseof first plate 40, the interior surface 44 is stepped so as to reduce inwidth in the radial direction toward rotation axis 28. Moreparticularly, surface 44 comprises a first annular-like radiallyouter-most surface 46, a stepped surface 47, an adjacent second radiallyinner intermediate annular-like surface 48, a further stepped surface49, and adjacent and radially innermost third annular-like third surface50. An aperture or hole 52 is formed through the first plate 40 centredon rotation axis 28.

The second plate 42 has an inner surface 54 which is composed of a firstradially outermost annular-like surface 56, first stepped surface 57, anadjacent and radially inner annular-like second surface 58, secondstepped surface 59, and. a radially innermost annular-like third surface60. Extending from the third surface 60 concentrically with rotationaxis 28 is stub shaft 62. A plurality of axially extending holes 64 areformed circumferentially about the first and second plates 40 and 42which are disposed to register with threaded holes 66 formed in theopposite ends of the cylindrical element 38. Bolts (not shown) arepassed through holes 64 and threadingly engage holes 66 for fasteningthe first and second plates 40 and 42 to opposite ends of thecylindrical element 38.

As seen in FIGS. 2 to 4, rotor body 26 is in the general form of ahollow cylinder being closed at a first end 68 and open at an oppositesecond end 70. The rotor body 26 is provided with reduced diameterportions 72 and 74 at the first and second ends 60 and 70 respectively.As seen most clearly in FIG. 1, the reduced diameter portions 72 and 74seat annular seals 76 and 78 respectively. Shaft 80 extends from thefirst end 68 concentric with rotation axis 28 through the hole 52 in thefirst plate 40. A short length 82 of the shaft 80 adjacent the first end68 is formed of an increased diameter. Bearing 83 is fitted onto shaft80 up to short length 82 and is sealed against surfaces 49 and 50 of thefirst plate 40.

Second end 70 is formed with a radially inwardly extendingcircumferential lip 84 and an axially extending annular boss 86. Stubshaft 62 can be received in the opening formed by the lip 84 and boss86. The juxtaposition of annular surface 90 of the lip 84 facing asecond plate 42 and the radially innermost circumferential surface 92 ofthe boss 86 form a sear for bearing 94. The bearing 94 has an inner race96 which receives, with an interference fit, the stub shaft 62.

A plurality of slots 96 (refer FIGS. 2 to 4) are formed in the rotorbody 26 which extend between and inboard of the first end 68 and secondend 70. As seen most clearly in FIG. 4, opposite ends 98 and 100 of theslots 96 are arcuate in shape and terminate on the reduced diameterportions 72 and 74 respectively. Slots 96 pass wholly through thethickness of the rotor body 26. In this particular embodiment, fourequally spaced slots 96 are formed circumferentially about the rotorbody 26. A radially extending groove 102 (refer FIGS. 1 and 3) is formedon an interior surface of first end 68 extending co-linearly with thedepth of each slot 96 at end 98. Each groove 102 extends to therotational axis 28 and runs into a corresponding groove 102 of anopposing slot 96.

Grooves 104 of similar configuration to grooves 102 are formed at theopposite end 100 of each slot 96 on an axially inner annular surface 106of the lip 84. However, as the grooves 104 only extend for the axiallength of lip 84, they do not pass through the rotational axis 28 nor dogrooves 104 of opposing slots 96 run into each other. Vanes 32 are inthe form of generally rectangular plates having arcuate, and moreparticularly convexly curved axial edges 108 and 110 and similarlycurved radially remote edge 112 and radially near edge 114. The axialedges 108 and 110 extend in a radial direction below the radially nearedge 104 so as to form protruding tabs 116 and 118 respectively betweenwhich a recess 120 is defined.

A biasing means in the form of a split sleeve 122 (refer FIGS. 1, 6A and6B) is disposed within the cylindrical element 38 for biasing the vanes32 radially outwardly from rotation axis 28 so that radially remote edge112 of the vanes 32 are in sliding and sealing contact with innersurface 34 with at most a layer of lubricant therebetween. The splitsleeve 122 is received in the recess 120 between tabs 116 and 118 ofeach vane 32 preventing axial movement of the sleeve 122 duringoperation of the apparatus 10. The sleeve 122 is made of a spring metaland dimensioned so as to maintain contact with all of the vanes 32during rotation of the rotor 24. It will be appreciated that the sleeve122 floats within the rotor 24 and adopts a position that is concentricwith and parallel to axis 30 of the housing 12. Generally, the outsidediameter of the sleeve 122 is equal to the internal diameter of housing12 minus twice the distance between the radially remote and near edges112 and 114 of a vane 32. However, in the specific case of the presentsplit sleeve the outside diameter is fractionally larger to provide adegree of spring loading the radially near edges 114 of the vanes 32.

When the apparatus 10 is fully assembled, the seal 76 overlies end 98 ofeach slot 96 and abuts axial edge 108 of each vane 32. Seal 78 issimilarly juxtaposed relative to the end 100 of slots 96 and axial edge110 of vanes 32. As a result, the seals 76 and 78 effectively seal theends of slots 96. Further, seal 76 sealingly abuts surfaces 47 and 48 offirst plate 40. Likewise, seal 78 sealingly abuts surfaces 57 and 58 ofthe second plate 42 Radially remote edge 112 of each vane 32 forms asliding seal against inner surface 34 of housing 12.

The curvature on the radially remote and radially near edges 112 and 114of the vanes 32 are shaped to suit the curvature of the inner surface 34of housing 12 and the curvature and location of the outer peripheralsurface of sleeve 122 respectively. The vanes 32 are of a length equalto that of cylindrical element 38 of the housing less a lubricatingtolerance, similarly the width of the slots 96 and thickness of vanes 32are relatively dimensioned so as to allow sliding of the vanes 32 withinthe slots 96 with a lubricating tolerance therebetween. By forming thesecomponents of the apparatus 10 with such a close tolerance together withthe inclusion of seals 76 and 78 fluid leakage within the apparatus 10is minimised.

An embodiment of the apparatus 10 with three vanes is -illustrated inFIGS. 7 and 8. In these Figures like numbers indicate the same featuresas described with reference to the embodiment shown in FIGS. 1 to 6B.

It will be appreciated that when the apparatus 10 comprises three (orany other odd number) of vanes 32 there will not be pairs ofdiametrically opposed grooves 102, which in the case of an apparatus 10with an even number of vanes 32, allows retraction of the vanes 32within the rotor beyond the central axis 28. In order to allow for suchover center retraction of vanes 32 in the present embodiment theinterior surface of first end 68 is counter bored about axis 28 to forma circular recess 103 of a depth equal to the depth of grooves 102.

In a further possible embodiment, the design of the vanes 32 can bemodified so that the radially inner edge 114 is tapered on both sides asshown in FIGS. 9A to 9C. The tapering is not necessary in the case ofthe rotor 24 supporting six or less vanes 32. However, it isparticularly advantageous for preventing interference between theradially inner edge 114 of adjacent vanes 32 in the case of a rotorhaving seven or more vanes when adjacent vanes are at or nearing fullretraction and extend over the axis 28.

From the foregoing description, it will be apparent to those skilled inthe art that the above embodiments include numerous advantages andbenefits over prior known radial vane motors and pumps including:

(a) The hollow rotor offers a considerable weight reduction whencompared with the conventional solid slotted rotor.

(b) A smaller diameter rotor can be employed with a greater degree ofeccentricity within a housing of a given internal diameter, resulting inan increase in effective vane extension with an attendant increase involumetric capacity.

(c) A greater number of vanes can be employed in the hollow rotor with alarger effective vane extension from the rotor than can be achieved withthe conventional slotted rotor, due to the fact that the grooves 102 ofthe hollow rotor intersect at the rotor axis 28 (see FIG. 3). It followsthat if the slots in a conventional rotor were to intersect at the rotoraxis, there would remain no segmental web at the root of the slots andthe rotor could not exist in this form. Conversely, because thesegmental web of the hollow rotor is at its outside diameter, theintersection of the grooves at the rotor axis does not affect theintegrity of the rotor. Therefore the hollow rotor motor has thepotential to deliver more power with less torque variation than theconventional unit having the same external dimensions, and as a pump,provide a greater fluid delivery with lower pulse amplitude than aconventional unit having the same external dimensions.

(d) The sleeve 122 supporting nearly the total length of the vanes 32ensures the proper vane 32 to housing sealing contact, preventingpartial retraction of the vanes when subjected to high operatingpressures as is the case with reliance being on fluid pressure for vaneextension, and preventing bowing of vanes under high fluid pressure whensuch vanes are only supported at their ends by cams or rings etc. Theprevention of fluid by-pass between the vanes 32 and inner surface 34 ofhousing 12 will result in improved efficiency of the device.

(e) In conventional radial sliding vane pumps and motors flat axial endsof the vanes are in constant contact with the surfaces of the end platesregardless of whether they are retracted or extended relative to therotor, which is a cause of significant lateral frictional drag. In thedescribed embodiment, because the end plates 40, 42 are recessed to theoutside diameter of the rotor body 26, the vanes 32 can only contact theend plates 40, 42 when they are extended beyond the outercircumferential surface 36 of the rotor body 26, therefore thefrictional drag attributable to the axial vane ends 108, 110 isconsiderably reduced by limiting their contact to approximately 50% ofthe end plate working areas. This frictional drag is further reduced bythe smaller contact area of the radiused axial vane ends 108, 110 asopposed to that generated by full thickness flat vane ends. This featurealso precludes the possibility of the rotor ends contacting the endplates as is common in conventional sliding vane units.

(f) Correctly toleranced seals 76, 78 prevent internal by-pass ofoperating fluid between adjacent or other chambers either around theaxial vane ends 108, 110 or via the unoccupied sections of the slots 96due to their common access to the operating fluid as is usual inconventional sliding vane type pumps or motors. This feature also limitsfluid loss or internal by-pass when the unit is in the stalled conditionunder operating load conditions.

Now that an embodiment of the invention has been described in detail, itwill be apparent to those skilled in the relevant arts that numerousmodifications and variations may be made without departing from thebasic inventive concepts. For example, although the housing 12 is shownas including separate end plates 40 and 42, one of those ends may beformed integrally with the cylindrical element 38 of the housing 12 andmachined to provide the relevant step surfaces. Also, while the rotor 24is shown as being a four vane (ie. four slot 96) greater or fewer vanescan be incorporated. In addition, the biasing element for biasing thevanes 32 radially outwardly is shown as being a split sleeve 122.However, other types of biasing elements can be used to achieve the sameeffect for example; a length of resilient tubing or rod such as may bemade from natural or synthetic rubber, or plastics material; a flatsection helical spring; a solid or hollow rod or tube of materialprovided with resilient circumferentially spaced inserts at intervalscorresponding to the location of the vanes 32; of a pressurised fluidsealed within the rotor body. All such modifications and variations aredeemed to be within the scope of the present invention, the nature ofwhich is to be determined from the foregoing description.

What is claimed is:
 1. An apparatus capable for use as a pump or motor, said apparatus comprising:a housing having sealed ends and provided with a cavity between said ends, said housing further including first and second ports both allowing fluid communication between the interior and exterior of said housing; a rotor having a substantially hollow rotor body supported by said housing for rotation within said cavity about a rotation axis extending parallel to and offset from a longitudinal axis of said cavity, said rotor body having opposite first and second ends which include respective portions of reduced diameter with respect to an intermediate portion of said rotor body; a plurality of slots formed in said rotor body extending between said opposite first and second ends and terminating in and inboard of said reduced diameter portions; and, a plurality of vanes, individual ones of which are slidably retained in separate slots for movement radially of said rotation axis; said vanes, rotor and housing juxtaposed so that a substantially sealed chamber is formed between adjacent vanes, an inner circumferential surface of said housing and said rotor, and wherein said first and second ports are disposed in different ones of said chambers.
 2. An apparatus according to claim 1, further comprising a seal about each of said reduced diameter portions, said seals being seated so as to cover the opposite ends of each slot and sealing abut axially opposite ends of said vanes.
 3. An apparatus according to claim 2, wherein said opposite ends of each slot are arcuate in shape.
 4. An apparatus according to claim 3, wherein each end of said housing is provided with a stepped inner surface formed by the junction of two faces and each seal can make sealing contact with both of said faces of an adjacent end of said housing.
 5. An apparatus according to claim 4, wherein a groove extending radially from each end of each slot is formed on a surface at each of said first and second ends interior of said rotor body for receiving axially opposite ends of a vane received in that slot.
 6. An apparatus according to claim 5, wherein said grooves on said interior surface at said first end of said rotor body extend beyond the centre of said rotor body.
 7. An apparatus according to claim 5, wherein said interior surface at said first end of said rotor body is provided with a circular recess centered about said rotation axis and the grooves formed on this interior surface extends radially from the end of the slots near said first end to said circular recess.
 8. An apparatus according to claim 1, wherein axially opposite edges of said vanes are formed with arcuate surfaces for sliding and substantially sealing contact with respective adjacent first and second ends of said housing.
 9. An apparatus according to claim 1, wherein the radially remote edge of each vane is formed with an arcuate surface for sliding and substantially scaling contact with said inner circumferential surface of said housing.
 10. An apparatus according to claim 1, further comprising biasing means disposed within said rotor body for biasing said vanes radially outwardly cowards said inner circumferential surface of said housing.
 11. An apparatus according to claim 10, wherein said biasing means comprises a resilient element extending in the direction of said rotation axis and adapted to act simultaneously on each of said vanes.
 12. An apparatus according to claim 11, wherein said resilient element comprises one of a split sleeve or a tube of resilient material; a length of natural or synthetic rubber tubing or rod; a tube or rod made of plastics material; a flat section helical spring fitted axially within said rotor body; a solid or hollow rod or tube of material provided with resilient circumferentially spaced inserts at intervals corresponding to the location of said vanes.
 13. An apparatus according to claim 12, wherein a recess is formed in the radially inner edge of each vane inboard of axially opposite ends of each vane for receiving said biasing means.
 14. An apparatus according to claim 10, wherein said biasing means comprises a pressurised fluid retained within said rotor body.
 15. An apparatus according to claim 1, wherein said rotor comprises a shaft extending from the first end of said rotor body and through an aperture formed in a first of said ends of said housing, wherein when said apparatus is used as a pump, torque can be applied to said shaft to impart rotational motion to said rotor, and when said apparatus is used as a motor, said shaft can act as a power take off.
 16. An apparatus according to claim 15, wherein the second end of said rotor body opposite said shaft is provided with a recess for receiving a stub shaft formed on a second of said ends of said housing for rotatably supporting said second end of said rotor body. 